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HIV Protease Genotypic Mutation Phenotyping (Phenotypic Resistance Testing)

Published: August 9, 2026Updated: August 16, 2026

This test evaluates how specific mutations in the HIV protease gene may affect the virus’s ability to resist certain antiretroviral medications. It helps tailor treatment to improve effectiveness.

Quick summary

["This test supports personalized HIV treatment by identifying potential drug resistance patterns."]

Medically reviewed by WellAlly Editorial TeamLast reviewed August 16, 2026Editorial policy

Key facts at a glance

LOINC
49661-2
Short code
HIV PI gene mut Islt Phenotyp
Synonyms
HIV PI gene mut Islt Phenotyp
Category
chemistry
Sample
serum
Container
Red-top tube (SST)
Units
N/A
Fasting
false
Population
adult
Sex
all
Age range
18–65 years
Method
phenotyping
CPT
86701
Specimen volume
5 mL
Stability
Room temperature: 4h, Refrigerated: 24h, Frozen: 7d
Hemolysis max
500
Lipemia max
1000
Icterus max
500
TAT
4–24 hours
Order
routine

Why This Test Is Done

Your healthcare provider may order this test if you’re on HIV treatment and show signs of treatment resistance, such as viral load that doesn’t decrease as expected. It’s also used in certain clinical trials or advanced HIV care settings.

How the Test Works

A small sample of your blood is taken and analyzed using a specialized immunoassay method. The test detects specific mutations in the HIV protease gene that could alter how the virus responds to medications.

Sample Collection

Whole blood is collected via a vein in your arm. The sample is processed and sent to a lab for analysis. This test does not require fasting or special preparation.

What to Expect After Testing

Results are typically reported within 1–2 weeks. Your doctor will discuss findings and adjust your treatment plan if needed. Follow-up visits may be scheduled to monitor viral load and response to therapy.

Clinical interpretation

How abnormal results are interpreted and what conditions they suggest.

◆Associated findings1

Short name

HIV Protease Mutation Phenotyping

Frequently asked questions

What does a positive result mean?
A positive result indicates the presence of specific mutations in the HIV protease gene that may contribute to drug resistance. This does not mean your treatment will fail outright, but your doctor may recommend changing medications to avoid resistance.
How long does it take to get results?
Results are usually available within 1–2 weeks from the time your sample is received by the lab. Your healthcare provider will contact you directly with the findings.
Can I stop taking my current HIV medication while waiting for results?
No, it’s important to continue taking your prescribed medications as directed. Stopping treatment without guidance could compromise your health or worsen viral resistance. Always follow your doctor’s instructions.
  1. 1
    MedlinePlus — Laboratory TestsSource
  2. 2
    Lab Tests OnlineSource
  3. 3
    Mayo Clinic — Tests & ProceduresSource

Click any link to access the full source. PubMed Central (PMC) links provide free full-text access.

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment.

Medical Disclaimer

This content is for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the guidance of a qualified healthcare provider with any questions you have about a medical condition, and never disregard professional medical advice or delay seeking it because of something you read here.

If you think you may have a medical emergency, call your local emergency number or go to the nearest emergency department immediately.

Medically reviewed by WellAlly Editorial Team Last reviewed August 16, 2026. · Read our editorial policy